トランスロコンにおける新生鎖の折り畳みの自由エネルギー
James Gumbart1, Christophe Chipot, Klaus Schulten
1Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Journal of the American Chemical Society
|April 29, 2011
まとめ
Secトランスロコンチャネルは,合成中に新生タンパク質の折り畳みを助けます. その性質はアルファヘリックス形成を好み,単にタンパク質を膜に挿入する以上の役割を果たすことを示唆しています.
科学分野:
- 分子生物学は分子生物学である.
- バイオフィジックス 生物物理学
- タンパク質の折りたたみ
背景:
- 新生タンパク質は,リボソームの出口トンネル内で折りたたみ始めます.
- 膜タンパク質を含む多くのタンパク質は,合成中にSecトランスロコンを通過します.
- トランスロコンは,脂質二重層にタンパク質の挿入を容易にする.
研究 の 目的:
- 新生鎖タンパク質の折りたたみに対するSecトランスロコンの影響を調査する.
- トランスロコン環境がタンパク質の二次構造形成に影響を与えるかどうかを判断する.
主な方法:
- アルファヘリックス形成のための平均力の潜在力を計算した.
- トランスロコンチャネル内の10-アラニンオリゴペプチドをシミュレートしました.
- ペプチド位置の関数として,形状状態 (アルファヘリックス,拡張) を分析した.
主要な成果:
- トランスロコンの支配的な形状状態は,水 (アルファ・ヘリケール型および拡張型) の形状を反映しています.
- トランスロコン環境は,バランスをアルファヘリカル状態にシフトさせます.
- トランスロコンの表面特性と変数直径が折り畳み平衡に影響を与える.
結論:
- Secのトランスロコンは,単に挿入だけでなく,新生タンパク質の折り畳みを促進します.
- トランスロコンの性質は,新興ポリペプチド鎖のアルファヘリックス形成を積極的に促進する.
- これは,タンパク質生物生成におけるトランスロコンの二重の役割を示唆しています.
関連する概念動画
Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Cotranslational Protein Translocation
Translocation of proteins across membranes is an ancient process that occurs even in bacteria and archaebacteria. In fact, the components of the translocation machinery are still conserved between prokaryotes and eukaryotes.
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Protein Folding Quality Check in the RER
ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...
Post-translational Translocation of Proteins to the RER
A sizable fraction of proteins destined for ER are first synthesized in the cell cytosol and then transported across the ER membrane–a process called post-translational translocation. Similar to cotranslationally translocated proteins, these proteins also use the Sec translocon complex to enter the ER lumen.
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Molecular Chaperones and Protein Folding
The native conformation of a protein is formed by interactions between the side chains of its constituent amino acids. When the amino acids cannot form these interactions, the protein cannot fold by itself and needs chaperones. Notably, chaperones do not relay any additional information required for the folding of polypeptides; the native conformation of a protein is determined solely by its amino acid sequence. Chaperones catalyze protein folding without being a part of the folded protein.
The...
The...
Molecular Chaperones and Protein Folding
The native conformation of a protein is formed by interactions between the side chains of its constituent amino acids. When the amino acids cannot form these interactions, the protein cannot fold by itself and needs chaperones. Notably, chaperones do not relay any additional information required for the folding of polypeptides; the native conformation of a protein is determined solely by its amino acid sequence. Chaperones catalyze protein folding without being a part of the folded protein.
The...
The...


